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HALO: A software tool for real-time head alignment in the MR scanner
Zhiying Zhao1,2, Gigi Galiana1, Cristofer Zillo3
1Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut, USA.
Magnetic Resonance in Medicine
|November 25, 2022
Summary
The Head ALignment Optimization (HALO) tool helps MRI subjects maintain consistent head positions across multiple sessions. This software improves data quality in longitudinal studies by ensuring accurate alignment and reducing signal variations.
Area of Science:
- Neuroimaging
- Biomedical Engineering
- Medical Physics
Background:
- Longitudinal MRI studies require consistent subject head positioning across sessions.
- Variations in head position alter tissue alignment with magnetic fields, impacting signal acquisition and susceptibility.
- Inconsistent alignment can significantly affect the quality and comparability of MRI data.
Purpose of the Study:
- To introduce Head ALignment Optimization (HALO), a software tool for active head alignment in MRI.
- To enable subjects to maintain precise head positioning between scanning sessions.
- To mitigate data quality issues arising from inter-session head position changes.
Main Methods:
- Development of HALO software providing real-time visual feedback on head position.
- Evaluation of HALO in a pilot study with seven healthy human subjects.
- Assessment of subjects' ability to actively align their heads to a reference position.
Main Results:
- Subjects successfully improved head alignment using HALO, achieving high precision ( < 2mm translation, < 2 degrees rotation).
- Significant improvements in head alignment were observed across sessions.
- A negative correlation was found between head rotation and BOLD signal similarity near air-tissue interfaces, confirming the impact of alignment on data.
Conclusions:
- HALO facilitates improved data consistency in longitudinal MRI studies by ensuring stable head alignment.
- Consistent susceptibility gradients across sessions can be maintained using HALO, enhancing BOLD data quality.
- The HALO software has been made publicly available for broader research use.
